Infertility in Sheep and Goats

Question 1

How can you measure the fertility of a flock?

Answer 1

% barren and % pregnant

Question 2

How can you measure the fecundity of the flock?

Answer 2

Number of lambs/kids born per pregnancy

Question 3

How can you measure the survival rate of a flock?

Answer 3

Number of lambs/kids that survive to weaning

Question 4

How can you measure the lambing percentage?

Answer 4

Number of lambs reared/weaned/sold per 100 ewes put to the ram

Question 5

What is the energy requirements for pregnant ewews?

Answer 5

Single 1.5 x maintenance

Twins 1.9 x maintenance

Question 6

What should you compare a flocks reproductive performance with?

Answer 6

Previous records

MLC flockplan record for local area or breed

Question 7

What are the factors responsible for poor lambing?

Answer 7

Poor conception rate
Poo ovulation rate
High embryonic/foetal death
Abortion/stillbirth/perinatal loss

Question 8

Of the factors responsible for poor lambing percentage, which leads to…

1. Increased single lambs
2. Increased barren ewes
3. Decreased ewes rearing a lamb

Answer 8

1. Poor ovulation rate
2. Poor conception rate and high embryonic death
3. High abortion/stillbirth/perinatal loss

Question 9

In general, what factors can cause poor conception rates?

Answer 9

Season
Reproductive tract abnormalities
Fertilisation failure
Phyto-oestrogens
Stress
Mal infertility

Question 10

How does season affect conception rate?

Answer 10

Breeding earl/late in breeding season results in poor conception rates because
= All animals may not be cyclic
= Possibilitys of short cycles in early breeding season
= Irregularity of cyclicity

Question 11

What reproductive tract abnormalities can affect conception rate?

Answer 11

Freemartins
Intersex
Ovarian hypoplasia
Ovarian cysts

Question 12

What are phyto-oestrogens? How do they affect conception rate?

Answer 12

Oestrogen like compounds produced by plants like red clover

Decreases conception due to changes in cervical mucous and sperm transport

Question 13

How can you avoid stress affecting conception rate?

Answer 13

Avoid transport, shearing, foot-trimming, vaccination, worming and dipping around breeding time

Question 14

What functional factors affect conception rate? How would you treat in sheep?

Answer 14

Pseudopregnancy/hydrometra/cloudburst
- Accumulation of aseptic fluid in uterues in presence of presistent CL
Reasons - lack on conception, early embryonic death, genetics
Treatment = PGF2-alpha and oxytocin

Question 15

Factors affecting ovulation rate in sheep?

Answer 15

Season
Age
Genotype/breed
BCS

Question 16

What is the ideal BCS at lambing for
Hill sheep
Lowland sheep

Answer 16

Hill - 3

Lowland - 3.5

Question 17

How does a high or low BCS affect lambing percentage?

Answer 17

Decreased conception rate
Decreased ovulation
Increased embryonic loss
Decrease lamb birth weight
Decreased colostrum production

Question 18

How can you manipulation ovulation rate in sheep? How does it work?

Answer 18

Season you bred in
Breed of sheep
BCS
Flushing

Increases follicle recruitment, selection and dominance

Question 19

Factors affecting/causes of early embryonic death in sheep…

Answer 19

Asynchrony between embryonic development and timing of P4

Dietary intake = overfeeding inversly related to P4 conc

Age = uterine environment

Mineral deficiencies (Se, I)

Infections (Toxo, Border disease)

Question 20

Factors affecting later foetal death in sheep..

Answer 20

Overfeeding in early pregnancy

Underfeeding in later pregnancy

Question 21

When does most foetal growth occur in sheep? What can happen if you overfeed?

Answer 21

In last trimester

Overfeeding leads to plactenal insuffiency

Question 22

Most common causes of late foetal death/abortion in sheep..

Answer 22

Chlamydophilia abortus
Toxoplasmosis
Campylobacter

Question 23

Causes of pernatal mortality?

Answer 23

Stillbirth
Diease
- Watery mouth, viral diarrhoea/toxo/chlamydophilia
Trauma
Mineral deficiency (Cu, Co)
Hypothermia
- Poor mothering
- Mis mothering